Thanks.. makes sense... Can I use x$bh or something to determine whether it's nicely squeezed into the buffer at some point in time?
On Mon, 12 Nov 2001 02:00:21 -0800, you wrote: >If rb's are small, then there is a good chance that >just when they are about to aged out of the buffer >cache, hey presto! another session needs them again - >so you end up with a nice scenario where they spend >their life in the cache and cause virtually no IO. > >As they get larger and larger, the time-before-reuse >time gets longer and longer - which will mean more and >more IO. Its the same for having lots of extents - >many moons ago this used to be due to txns needing >their own extents. Oracle lifted this restriction >somewhere in v7, but it still makes sense to have 20 >or so extents, because then when a rollback segment >increases in size, it does it in nice 5% increments - >keeping the probability of it all fitting in the cache >high. > >hth >connor > > --- Doug C <[EMAIL PROTECTED]> wrote: > OK.. this may >be a little naive..and maybe I'm just >> jogging my own memory, but >> here it goes... >> There are a couple schools of thought on rollback >> segments as near as I can >> figure. Some like to set optimal, and some don't. >> The one's that don't like >> to shrink them at night or once daily or some other >> variation.. >> >> Question: Why bother? If they get big and you have >> the room, so what? They >> won't have to extend tomorrow, no? If you're >> concerned about space, why not set >> a good maxextents or a limit on the filesize.. >> >> What's the problem with them getting large? >> >> Thanks, >> Doug >> >> >> >> >> -- >> Please see the official ORACLE-L FAQ: >> http://www.orafaq.com >> -- >> Author: Doug C >> INET: [EMAIL PROTECTED] >> >> Fat City Network Services -- (858) 538-5051 FAX: >> (858) 538-5051 >> San Diego, California -- Public Internet >> access / Mailing Lists >> >-------------------------------------------------------------------- >> To REMOVE yourself from this mailing list, send an >> E-Mail message >> to: [EMAIL PROTECTED] (note EXACT spelling of >> 'ListGuru') and in >> the message BODY, include a line containing: UNSUB >> ORACLE-L >> (or the name of mailing list you want to be removed >> from). You may >> also send the HELP command for other information >> (like subscribing). > >===== >Connor McDonald >http://www.oracledba.co.uk (mirrored at >http://www.oradba.freeserve.co.uk) > >"Some days you're the pigeon, some days you're the statue" > >__________________________________________________ >Do You Yahoo!? >Everything you'll ever need on one web page from News and Sport to Email and Music >Charts >http://uk.my.yahoo.com >-- >Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Doug C INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
